53BP1 orchestrates sequence feature of RAG targets to balance DNA repair outcomes during V(D)J recombination [PRO-seq]

However, 53BP1, as a key DNA damage response (DDR) factor promoting c-NHEJ, is dispensable for V(D)J recombination. Here, we report that 53BP1 orchestrates sequence strength of RAG targets to shape end-joining features during V(D)J recombination.

Deficiency of 53BP1, rather than other DDR factors, specifically increases junctional microhomology (MH) of cryptic RSS (cRSS) recombination instead of RSS recombination. Depletion of RIF1 or Shieldin, downstream factors of 53BP1, partially mimics the phenotypes of 53BP1-deficiency. Notably, loss of RNF168, rather than other classical resection and alternative end-joining factors, is sufficient to fully rescue 53BP1-deficiency-mediated increase of junctional MH during cRSS recombination.